基于ASTER GDEM数据的青藏高原东部山区地形起伏度分析

以青藏高原东部山区为研究区,基于高空间分辨率的ASTER GDEM数据,通过AML语言编程调用ArcGIS中用于邻域分析的focal函数,计算不同邻域尺度单元下地形起伏度。研究表明:邻域尺度单元大小对地形起伏度计算至关重要,起伏度值先随邻域尺度单元面积增大而快速增大,当邻域尺度单元面积达一定阈值后,其增大速度开始减缓并趋于平稳,且在增速减慢过程中存在一明显拐点,即最佳邻域尺度单元。通过高差显著性变化检验法,确定最佳邻域尺度单元为5.0625km2,据此制作地形起伏度分级图,发现研究区自西北向东南地形起伏度逐步增加,地势以中度起伏(200～500m)为主。

Analysis on the Relief Amplitude Based on ASTER GDEM Data in Mountain Area of Eastern Tibetan Plateau

Relief amplitude is an indicator that can reflect change of rolling surface topography.It is widely used in terrain mapping,evaluation of resources and the environment and so on.This paper takes mountain area of the eastern Tibetan Plateau as study area.The relief amplitude in different neighborhood scale were calculated by AML programming invoking focal functions in ArcGIS base on ASTER GDEM data with high spatial resolution.The researches show that:Neighborhood scales have a critical effect on relief amplitude.In beginning,the values of relief amplitude increase rapidly with growing in area of neighborhood statistics units.But when the area of neighborhood units reaches a certain threshold value,the growth rate begins to slow down and stabilize.And there is a significant inflection point that is best neighborhood-scale unit when the growth rate begins to slow down.The best neighborhood-scale unit for measuring relief amplitude is 5.0625 km2 by significance test.Class of relief amplitude is got,and it is found that the relief amplitude gradually increases from northwest to southeast in study area.The relief amplitude between 200 m to 500 m has the highest proportion,about 40.12%,and level of 500~1 000 m accounts for 26.05%.Therefore fluctuation of terrain is mainly moderate in study area.